1. Field of the Invention
The invention relates to gauges for measuring one-and two-dimensional time-resolved velocities of steady, unsteady and oscillatory nature in both laminar and turbulent fluid flows. More particularly, it refers to an instrument for resolving the magnitude of velocity and two-dimensional velocity vectors through different embodiments in standard and hostile fluid environments such as abrasive suspensions, slurries, and highly corrosive discharges typically found in geothermal wells, oil wells or hydrothermal vents.
2. Description of the Prior Art
Flows encompass turbulent, laminar, steady, unsteady, or reversing movements of fluids. To quantify their velocity, adequate size and frequency responses of velocity probes are necessary to resolve the flow-inherent scales, both in frequency domain and wavenumber space. Customarily more than one velocity sensor is needed to cover the range of time variability in natural flows ranging from rivers to oceanic applications as well as in engineering projects. Complications may arise in the field, where fluids are often not as clean or homogeneous as experienced in aerodynamic and fluid dynamic laboratory set ups. Instead, the fluids are frequently multi-phase mixtures composed of suspensions of cohesive, cohesionless or mixed sediments from low to high concentrations, containing also biological solutes, bacteria, and gases. Exudates and debris might as well be included. Even liquid-gas or liquid-liquid mixtures may be present. As a result, sophisticated measuring techniques usable in laboratory flows such as optical or acoustical velocity transducers may not be applicable in the field due to ambiguous calibration relationships in heterogeneous mixtures of biotic and abiotic origins, difficulties to deploy or mount the probes and associated electronics, or attrition and corrosion of the device by the fluid. Latter is particularly true when high-pressure, high-temperature, chemically aggressive flows are to be investigated such as discharges from hydrothermal or geothermal vents (on the ocean floor), or from oil wells. A velocity gauge is needed to resolve one or two-dimensional motions with adequate spatial and temporal responses to provide instantaneous speed and velocity vectors not only in homogeneous fluids but also in aggressive, hostile and suspension-bearing flows such as hydrothermal vents, oil wells, slurries, fluid muds and natural suspensions with steady, unsteady and oscillatory time histories. The term `instantaneous` is used to define short-term averaged signals of durations comparable to or shorter than fluctuations in the flow representing at least 90% of the turbulent kinetic-energy frequency spectrum.